1. Field of the Invention
The invention relates to a denture cleanser tablet composition and to methods of making and using a denture cleanser tablet composition.
2. Description of Related Art
Full or partial dentures are intended to be worn in the mouth to replace missing teeth. Like teeth, dentures should be cleaned regularly to maintain good oral health. Like teeth, dentures should also be cleaned regularly for cosmetic reasons.
Unlike teeth, dentures can be removed for cleaning. Dentures are also made of durable materials, such as acrylic polymers, that can withstand harsher cleaning conditions than teeth. As a result, dentures can be, and are, exposed to harsher cleaning conditions than teeth.
Dentures are typically cleaned in one of two ways: either the dentures are soaked for some time in a cleansing bath or dentures are brushed with dentifrices or specially formulated cleansing creams.
Brushing with creams has the advantage of supplementing the cleaning formulation with mechanical action. Unfortunately, as with teeth, spots on the dentures can be missed or overlooked during the brushing process. As a result, the denture material can degrade over time, and remaining teeth and gums of the user may be exposed to disease agents and undesirable cosmetic consequences.
Soaking in a cleansing bath offers the advantage of reaching every part of a denture for cleaning. Full immersion of the denture in the bath allows the cleansing composition to reach areas that cannot be reached by ordinary brushing with creams.
Cleansing baths are not usually sold as such. Typically, the active ingredients are sold in solid form, as a denture cleanser powder or tablet, or in concentrated liquid form. The active ingredients are then dissolved in a water bath to form the cleansing bath.
Unfortunately, soaking surrenders the advantage of mechanical scrubbing found with creams and dentifrices. To compensate for this loss of mechanical cleaning, denture cleansing tablets and powders usually contain an effervescent system and strong chemical cleaning agents.
Strong chemical cleaning agents, such as bleaches, can impart an unpleasant taste or odor to soaked dentures, however. Thus, denture cleanser manufacturers face a trade off between efficacy and cosmetic and organoleptic considerations.
Finding strong denture cleanser agents that do not impart unpleasant qualities to the dentures is an ongoing task. Acceptable agents must be nontoxic, nonstaining, and water soluble. Although not a strict requirement, the cleanser should not precipitate in the bath during cleaning to coat the denture or leave an unsightly residue in the bath.
U.S. Pat. No. 2,409,718 to Snell et al., issued Oct. 22, 1946 was an early approach to the denture cleanser agent dilemma. That patent used a water soluble salt of 2,2' dihydroxy-3,5,6,3',5',6' hexachlorodiphenylmethane as a disinfectant combined with sodium perborate as an oxidizing agent, tetrasodium pyrophosphate as a scale disintegrating material, sodium lauryl sulfo-acetate as a surface tension lowering agent, tricalcium phosphate as an anticaking agent, oil of peppermint and sodium chloride to make a denture cleanser material.
Bleaching or oxidizing materials, such as the sodium perborate in the Snell patent, have been popular ingredients in denture cleanser compositions for some time. U.S. Pat. No. 5,571,519 to Synodis et al., issued Nov. 5, 1996, teaches a two-layer tablet with a bleaching agent, such as perborate and persulfate, in combination with a flavoring agent. The separate layers prevent deterioration of the flavor by the bleaching agent on the shelf.
U.S. Pat. No. 2,498,343 to Rider et al., issued Feb. 21, 1950 (Rider I) and U.S. Pat. No. 2,498,343 to Rider et al., issued Feb. 21, 1950 (Rider II) both report oxidizing agents, such as sodium perborate and sodium percarbonate, in denture cleanser formulations. The oxidizing materials are used in combination with other ingredients, including sodium hexametaphosphate, a compound that helps with scale reduction and retards precipitation of cations in the cleansing bath.
Hexametaphosphate has also been used as an ingredient in denture cleansers.
U.S. Pat. No. 4,217,234 to Krisp et al., issued Aug. 12, 1980 (Krisp I) and U.S. Pat. No. 4,256,599 to Krisp et al., issued Mar. 17, 1981 (Krisp II) are directed to denture cleansing tablets. Krisp I is directed to a single layer tablet for "fast" cleansing of dentures, i.e., the tablet cleans dentures within about five minutes of immersion. The tablet contains sodium bicarbonate, sodium hexametaphosphate, acid disodium pyrophosphate, Caro's Acid (peroxymonosulfuric acid), amidosulfonic acid, ethylenediamine tetraacetic acid, polyethylene glycol, sodium polyacrylate, a surfactant, sodium benzoate, dialkyl thiourea and a nonionogenic fluorochemical to increase wetting. Krisp II is directed to a two-layer tablet. The tablet contains sodium bicarbonate, sodium hexametaphosphate, sulfamic acid, ethylenediamine tetraacetate (EDTA), polyethlyene glycol, a surfactant, sodium pyrophosphate, an alkali metal salt of peroxymonosulfuric acid, starch bentonite, dye, dibasic calcium phosphate and other optional ingredients.
U.S. Pat. No. 5,055,305 to Young, issued Oct. 8, 1991, is directed to a denture cleansing tablet with an inorganic persalt bleaching agent and an organic peroxyacid bleach precursor in combination with an effervescent system.
EDTA, especially in combination with oxidizing agents, has also been used in denture cleanser formulations for some time. U.S. Pat. No. 5,476,607 to Eoga et al., issued Dec. 19, 1995, (and related U.S. Pat. Nos. 5,486,304 and 5,384,062) looks to a combination of perborate and persulfate in a denture cleanser. The composition also uses enzymes and EDTA.
A similar patent, U.S. Pat. No. 5,015,408 to Reuss, issued May 14, 1991, is directed to a denture cleanser tablet with perborate, potassium monopersulphate, and an activator such as tetraacetyl ethylene diamine (TAED).
U.S. Pat. No. 4,701,223 to Eoga, issued Oct. 20, 1987, is directed to a spray-on denture cleanser having a detergent, a chelating agent, such as EDTA, and water.
U.S. Reissue Pat. No. 32,771 to Eoga, reissued Oct. 25, 1988, is directed to the combination of perborates, a fluorocarbon, and a phosphate salt. One of the sequestrants in the patent may be EDTA.
A smear layer remover is disclosed in U.S. Pat. No. 5,120,460 to Asai et al., issued Jun. 9, 1992. This patent uses a solution of EDTA in combination with a carboxyvinyl polymer, which thixotropically gels the solution, and an antibacterial agent.
Variants of EDTA have also been used. A tartar control agent comprising phosphonic acid derivatives is placed in a denture cleanser in U.S. Pat. No. 4,851,146 to Hosoi et al., issued Jul. 25, 1989. One possible derivative is ethylenediamine tetramethylphosphonic acid.
Enzymes are another material that can be used in denture cleansers. U.S. Pat. No. 4,486,330 to Yoshida et al., issued Dec. 4, 1984, uses .beta.-1,3-glucanase to remove Candida albicans, a major cause of denture stomatitis, from dentures. EDTA is among the denture cleanser ingredients listed in this patent.
Denture cleansing baths are not the only potential use for a tablet, concentrate or powder cleaning material in the oral health care field, of course.
Tablets, concentrates or powders can be used with water to make mouthwashes, as in U.S. Pat. No. 3,590,121 to Schiff et al., issued Jun. 29, 1971. A chewable effervescent tablet for cleaning teeth is the subject of U.S. Pat. No. 4,753,792 to Aberg, issued Jun. 28, 1988. The tablet contains fluoride, an effervescent system, and a combination of a filling and polishing agent, such as sorbitol or mannitol, and a foam stabilizing agent such as sodium lauryl sulfate.
U.S. Pat. No. 5,437,856 to Lukacovic et al., issued Aug. 1, 1995, is directed to oral gels, toothpastes and mouthwashes containing an enzyme, a surfactant, a chelating agent and a fluoride ion source.
A water soluble effervescent tablet for use in the water bath of ultrasonic cleaning equipment is the subject of U.S. Pat. No. 5,529,788 to De Senna, issued Jun. 25, 1996. The tablet contains a proteolytic enzyme and helps ultrasonic equipment clean dental and medical instruments.
Tablets, concentrates and powders can also be used in fields other than oral health care in cleaning systems where water can be supplied independently of the cleaning agent. Cleaning systems that are not designed for oral health care, however, have very different operating constraints, and great care should be taken before adapting such cleaning systems for oral health care use.
Cleaning agents in the form of tablets, concentrates or powders are usually found outside the oral health care field as cleaners for various household uses, i.e., as laundry detergents, dishwashing detergents and hard surface cleaners. There are many formulations for carrying out various cleaning tasks. One example of such a system is found in U.S. Pat. No. 5,306,439 to Lockhart, issued Apr. 26, 1994. This patent is directed to a jewelry cleaner having tetra sodium ethylenediamine tetraacetic acid (EDTA), sodium lauryl sulfate, and an alkyl aryl sulfate in a compressed effervescent tablet.
A fabric cleaner is addressed in U.S. Pat. No. 4,299,717 to Cottrell et al., issued Nov. 10, 1981. This patent claims an alkaline detergent for fabric washing containing a detergent surfactant, an alkali metal carbonate, a pyrophosphate and phosphate builder salts.
U.S. Pat. No. 5,482,646 to Mazzola, issued Jan. 9, 1996, discusses a laundry detergent for cold water with a reduced detergent residue. The laundry detergent is claimed to contain a detergent builder (at least one-third being sodium carbonate), a granular detergent and a particulate anionic surfactant coated on the surface of the detergent granules.
Tablet or powder cleaning systems may also be used in place of traditional aqueous solution cleaners, as in U.S. Pat. No. 4,502,892 to Westermann et al., issued Mar. 5, 1985. This patent is directed to a pelleted windshield cleaner that is dissolved in water before use. The pellets contain a water soluble alkali metal polyphosphate of high molecular weight, an alkali metal carbonate or hydrogen-carbonate, a crystalline material producing an acid reaction in aqueous solution, an anionic or nonionic surfactant, and a filler, such as an alkali metal phosphate or sulfate.
A liquid laundry detergent with enzymes is the subject of U.S. Pat. No. 4,169,817 to Weber, issued Oct. 2, 1979. This patent is directed to a stabilized enzyme system that is derived from Bacillus subtilis and that increases the effectiveness of the detergent against proteinaceous and carbohydraceous soils. This system is reported to be stable in a composition of detergent builders, including sodium hexametaphosphate, and surfactants.
Despite the efforts in the oral health care field to develop highly effective denture cleanser systems, the search for ways to maximize the effectiveness of cleaning systems while avoiding the unpleasant consequences of strong chemical agents continues.